Rheological and spectroscopic study of luminescent Eu3+ -doped gellan gum

Abstract

Gellan gum (GG) can be prepared in the form of a gel and be used as a versatile and functional biomaterial. GG can come in the acetylated (HAGG) and deacetylated (LAGG) forms. There are gaps in the study of these GG matrixes associated with lanthanide ions, well-known for their luminescent properties. In this work, we have doped HAGG and LAGG with Eu3+ ions and used the resulting HAGG_Eu and LAGG_Eu gels as structural probe in spectroscopic analyses. The presence of Eu3+ ions in the GG polymeric network gradually changed the viscoelastic properties of the HAGG_Eu and LAGG_Eu gels, as confirmed by oscillatory rheology analysis. The spectroscopic study of the films obtained from HAGG_Eu and LAGG_Eu revealed how the Eu3+ ion interaction occurs, thereby improving our understanding about their structures. To intensify the emission process in the LAGG_Eu films, we added the β-diketone ligand TTA (2-thenoyltrifluoroacetone) to them, that acted as a sensitizer for Eu3+ ions. In conclusion, we have been able to obtain luminescent films based on GG. In addition, we have carried out an unprecedented structural study of the Eu3+-containing films, which have promising luminescent properties for use as new biocompatible systems.